1. Field of the Invention
This invention relates to product-retaining packages, and more particularly to such product-retaining packages comprising a substantially rigid plastic support (or card) sealed to a corresponding paperboard support (or card) with at least one substantially flexible plastic product compartment and with printing on at least one or both sides side of the combination plastic and paperboard package.
2. Related Art
Presently used packages include paperboard in combination with flexible PVC film (stretch pack) and preformed non-linear unprinted semi-rigid plastic materials sealed to, or in combination with printed paperboard materials (clamshells, blister packs and others). Clamshell-type packages have a 100% plastic exterior (on front and back) such that the rigid plastic structure is on the outside and printed paperboard is contained inside, which results in elevated package component costs as well as inherent potential for printed material damage. No existing packaging option provides for flexible PVC film in combination with both paperboard and printed semi-rigid PVC film.
The plastic or PVC component of blister and clamshell-type packages cannot be satisfactorily printed using lithographic or flexographic methods because of the irregular non-linear surfaces created by the thermoformed plastic exterior. Additionally, a minimum distance between the edge of the product and the edge of the paperboard (or plastic) must be maintained for structural and sealing purposes. Stretch pack and clamshell-type packages require a wide seal band (common for paperboard) on the inside edge of the card border. Also clamshell-type packages have the same limitation when preformed cavities of rigid plastic are close to the edge of the package requiring a flange area. The flange and seal band areas are cosmetically unappealing and limit the surface area for design and printing graphics. This is a major disadvantage because the extra size of the package consumes valuable retail shelf or hanging space which then restricts potential use of the product-retaining package.
Other disadvantages of existing paperboard containing packages (blisters, clamshells, stretch pack) are ease of structural damage. bending and wrinkling of the paperboard components either on the interior or exterior of the package.
Often, in transport and handling, packages containing paperboard are bent and wrinkled. This is a great disadvantage and very cosmetically unappealing. The exterior PVC area on clamshell style packages consisting of semi-rigid PVC (and other plastic materials) is not easily damaged in this manner, however, clamshells are a costly packaging alternative. Clamshell packaging costs are elevated because of excessive amounts of plastic material on the front and back of the package, labor intense assembly required in some applications, costly molds need to thermoform the cavities, and printed paperboard which is required to display graphics (this paperboard is also subject to damage).
The varying sheet thickness of paperboard causes imprecise printing which limits the flexographic or lithographic printing quality. Moreover, 100% paperboard packages have imprecise folding, slitting, and feeding characteristics on automated sealing equipment which is a further disadvantage of using predominantly paperboard in product-retaining packages.
Also, because of preformed rigid cavity construction, clamshell-type packages are not linear and flat, therefore they do not de-nest and feed efficiently. They also cannot be printed. Because the plastic is not printed, a printed paperboard insert is required as an additional material for graphics display.
Several different combinations of printed semi-rigid plastic (PVC and other materials) and flexible PVC film in combination with printed (or unprinted paperboard) are possible. Some finished packages have windows on the front and on the reverse side. Some finished packages have windows on the front and on the reverse side. Some windows are on one side only and some packages have multiple compartments with one or more sides. However, all combinations use essentially the same type materials and process for their manufacture.